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Theories of aging by Nancy V.Karp, Slides of Life Sciences

Theories of aging in describes aging from biological, physiological and psychosocial perspective and explain full life theories and mature life theories.

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2021/2022

Uploaded on 03/31/2022

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Theories of Aging
Nancy V. Karp, Ed.D., P.T.
nvkarp@gmail.com
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Theories of Aging

Nancy V. Karp, Ed.D., P.T.

nvkarp@gmail.com

Objectives

This presentation will describe aging from both a

biological/physiological and a psychosocial

perspective.

Biological/physiological theories will be presented in

two main categories, program theories and error

theories.

Psychosocial theories will be discussed in two main

categories, full-life theories and mature-life theories.

Is There a Fountain of Youth?

What is Aging?

The gradual and spontaneous changes that

occur in maturation from infant to young adult.

These changes create a normal physiologic

decline seen in middle and late adulthood.

Changes during puberty

Graying of hair

Senescence

The process by which a cell looses its ability to

divide, grow, and function. This loss of function

ultimately ends in death.

A degenerative process, only.

Has no positive features.

Life Expectancy

Some Factors Influencing Your Life Expectancy

Heredity

Disease Processes

Medical Treatment

Lifestyle Choices

Nutrition

Theories of Aging

“The link between genes and lifespan is unquestioned. The simple observation that some species live longer than others -- humans longer than dogs, tortoises longer than mice -- is one convincing piece of evidence.”

The National Institute on Aging

The Two Main Aging Theory Categories

Programmed Theories Aging has a biological timetable or internal biological clock. Error Theories Aging is a result of internal or external assaults that damage cells or organs so they can no longer function properly.

Many theories are a combination of programmed and error theories.

Programmed vs. Error Theories

Programmed Theories

Programmed

Senescence Theory

Endocrine Theory

Immunology Theory

Error Theories

Wear and Tear Theory Rate-of-Living Theory Cross-linking Theory Free Radical Theory Error CatastropheTheory Somatic Mutation Theory

Programmed Senescence Theory

The result of sequential switching “off” or “on” of

specific genes.

Example – “Hayflick’s Limits”

  • Fibroblasts removed from umbilical cord & cultured
  • Fibroblasts divide and repeated until ~ 50 divisions
  • Will not divide past this point

Telomeric Theory

This is an extension of the “Hayflick Limit.”

Telomeres are specialized DNA sequences at the end

of chromosomes.

  • They shorten with each cell division.
  • When the telomeres become too short, the cell enters the senescence stage.

In the normal process of DNA replication, the end of the

chromosome is not copied exactly, which leaves an

unreplicated gap.

Telomeric Theory

The enzyme, telomerase, fills the gap by

attaching bases to the end of the chromosomes.

As long as the cells have enough telomerase to

do the job, they keep the telomeres long enough

to prevent any important information from being

lost as they go through each replication.

  • With time, telomerase levels decrease.
  • With decreasing telomerase levels, the telomeres become shorter and shorter.